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Yellowstone to assess climate change risks when rebuilding after flood


HELEN, Mont. – Shaded by hills and rock faces, the North Entrance Road to Yellowstone National Park normally traces the river, transporting visitors from the outside world to a very different world teeming with wildlife and geothermal features of another world.

But large chunks of pavement have now disappeared from this crucial tourist corridor, swept away by a severe May storm that swelled the Gardner River and sent mud and rocks tumbling down the hills. Some stretches of road were erased or left with half lane – if that’s the case – with jagged edges that made the river look like it had taken big bites of asphalt.

In its 150th year, Yellowstone, the nation’s oldest national park, stands at an existential crossroads in the age of climate change. It will be rebuilt after flood damage, which forced the two northern entrances to close for months. But the question is how, especially given the likelihood that flash floods, drought, wildfires and heat will drastically change how the park operates.

“We have a good idea of ​​what lies ahead,” said Betsy Buffington, Northern Rockies regional vice president for the National Parks Conservation Association. “What does rebuilding mean in this larger context? »

In the days after the storm, Yellowstone Superintendent Cam Sholly suggested that old disaster measuring sticks had become obsolete as climate change took hold. He described the recent storm as a “millennial event, whatever that means these days”.

“They seem to be happening more and more frequently,” he added.

The biggest impending factor is a rapidly changing climate, which experts say contributed to record flooding. According to NASA, an atmospheric river and warm temperatures resulted in the equivalent of four to nine inches of rain in precipitation and snowmelt combined. The Yellowstone River just north of the park peaked at 13.88 feet, breaking the previous record of 11.5 feet set in 1918.

If, as Mr. Sholly suggests, “millennial events” will happen much more often, National Park Service officials need to think hard about whether to rebuild roads and buildings in the same places they were washed away. In some places, he said, parts of the road slipped 80 feet into the river.

With more rain-on-snow events, more flooding is expected. “A lot of the roads are historic stagecoach roads,” said Cathy Whitlock, a paleoclimatologist at Montana State University in Bozeman and author of a study on climate change in the park. “The park needs to think about extreme events, the kind we’ve never seen before, and fortify its buildings, roads and infrastructure.”

Across the country, national parks face similar challenges. They are particularly vulnerable because many are found at higher elevations, where the thinner atmosphere leads to warmer temperatures and where the disappearance of snow leads to greater heat absorption by the ground, according to a 2018 study.

For now, Yellowstone officials are working to ensure visitors can have some semblance of a vacation the rest of the summer. The southern part of the park has reopened and the northern part was due to open on Saturday in time for the holiday weekend, although visitors cannot access it from the north.

The Federal Highway Administration announced fast-release funding of $60 million to allow for temporary repairs in the park, but long-term reconstruction costs will increase much more. The Associated Press recently estimated that the price could exceed $1 billion, although the National Park Service has yet to calculate a ballpark figure. “I’m not going to give a high level number at this point,” Mr. Sholly said in an interview. “It’s going to be expensive.”

No decision has been made on the location of the new road between Gardiner, a gateway community at the northern entrance, and the park headquarters in Mammoth. Mr Sholly said rebuilding the same river route could be untenable as climate change made another catastrophic flood more likely.

He said the washed-out stretches of road are “probably less than two miles, but they’re in the worst areas for that to happen.” Aerial footage shows that in some places floodwaters have washed away the entire causeway and reclaimed the river channel.

“I would prefer to see this river corridor restored,” he said.

The park’s northeast entrance also remains closed after parts of the main road collapsed in the storm, cutting off the nearby tourist towns of Silver Gate and Cooke City.

No entrance should reopen before the fall.

The problem this time was water flooding, but the opposite concern also worries scientists. The snow line climbs higher in the area, and parched grasses, brush and tree limbs have become ready fuel for large wildfires.

Last year, wildfire fuels were so dry that the park suspended its policy allowing natural fires to burn. The park reduced fuels by mechanical means around hotels, stores, and other buildings to provide defensive space in the event of a wildfire.

“We’ve seen fires burning where we haven’t seen them before,” Mr Sholly said. “Last year we had some of the hottest water temperatures and some of the lowest water levels we’ve seen in our rivers and streams.”

The park region, which warmed by 2.3 degrees Fahrenheit between 1950 and 2018, is likely as hot or hotter than it has been in 20,000 years, according to paleoclimate records cited in the study. of Mrs. Whitlock. The prevailing level of the snow zone in 1950 was around 7,000 feet and by 2100 could be 9,500 feet, according to projections.

By 2060 to 2080, the park is expected to be 5 to 6 degrees Fahrenheit warmer than temperatures just before and after 2000, according to Ms Whitlock’s study. Without mitigation, the temperature could rise by 10 degrees by the end of the century.

Hotter, drier temperatures could also alter the park’s famous geothermal features, providing them with less water. A recent study found that during a mega-drought in the 13th century, the Old Faithful geyser stopped erupting for decades. Geothermal characteristics depend on a balance between water and heat.

Researchers are studying wildlife migration corridors outside the park to make sure Yellowstone’s famous assortment of species, from grizzly bears to antelope, have ways out of the park as it gets warmer . “If we want to protect Yellowstone’s iconic wildlife, we need to protect the areas wildlife needs to migrate, move and maintain genetic diversity,” said Ms Buffington, vice president of the conservation association.

Cultural assets are also under threat. So far, it appears the only building in the park to be damaged was a 1930s backcountry ranger cabin that was swept away, Mr Sholly said. An inventory of archaeological sites is underway to see if they have suffered damage from the torrential rains.

As park officials rebuild, they will consider all potential impacts of climate change.

“What are the things that we may not have thought about 10, 20 or 30 years ago but will think about in 10, 20 or 30 years time?” said Mr. Sholly.

nytimes

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